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7fec8a5de6
The 53807741fb added a configure check
for 64-bit atomic operations that were not previously enabled on some
32-bit ABIs.
However, the NPTL semaphore code casts a sem_t to a new_sem and issues
a 64-bit atomic operation for __HAVE_64B_ATOMICS. Since sem_t has
32-bit alignment on 32-bit architectures, this prevents the use of
64-bit atomics even if the ABI supports them.
Assume 64-bit atomic support from __WORDSIZE, which maps to how glibc
defines it before the broken change. Also rename __HAVE_64B_ATOMICS
to USE_64B_ATOMICS to define better the flag meaning.
Checked on x86_64-linux-gnu and i686-linux-gnu.
Reviewed-by: Wilco Dijkstra <Wilco.Dijkstra@arm.com>
50 lines
1.8 KiB
C
50 lines
1.8 KiB
C
/* Copyright (C) 2003-2025 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#ifndef _ATOMIC_MACHINE_H
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#define _ATOMIC_MACHINE_H 1
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/* Some macros can be overridden if the architecture requires some specific
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atomic operations or provides extra optimizations.
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* atomic_max (mem, value): atomically set the maximum value of *mem
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and value to *mem. Used on malloc statistics collection.
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* atomic_full_barrier: defaults to __atomic_thread_fence (__ATOMIC_SEQ_CST)
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* atomic_read_barrier: defaults to __atomic_thread_fence (__ATOMIC_ACQUIRE)
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* atomic_write_barrier: defaults to __atomic_thread_fence (__ATOMIC_RELEASE)
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* atomic_spin_nop: arch-specific instruction used on pthread spin lock
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and adaptive mutexes to optimize spin-wait loops.
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*/
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#include <bits/wordsize.h>
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/* NB: The NPTL semaphore code casts a sem_t to a new_sem and issues a 64-bit
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atomic operation for USE_64B_ATOMICS. However, the sem_t has 32-bit
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alignment on 32-bit architectures, which prevents using 64-bit atomics even
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if the ABI supports it. */
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#if __WORDSIZE == 64
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# define USE_64B_ATOMICS 1
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#else
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# define USE_64B_ATOMICS 0
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#endif
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#endif /* atomic-machine.h */
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